to form them when cut above the neck. Why not fire form them straight?? there are ways to fire form in dies also.

I tried fireforming the brass for my 357AR which is 1.595" trim, 1.605" max length. That included the entire shoulder on the 223 case and a touch of the neck. I worked up the wax plug and charge until it was a max charge for a 357mag and quick powder. It didn't open up the case enough after repeated firings. . So I tried necking up the case to .357" and tried the same thing. with pretty much the same result, an undersized case. The web on the cases is thick and takes a near full charge with a bullet to fireform. What I did was to just make an expander die that would open up the 223 cases including all but the bottem 1/4 of the case which takes a near full charge to expand all the way. To address the bump left over from the neck I made a roller tool which removes any hint of the bump. Otherwise the bump will stay there through at least 12 firings at 55k-62k PSI (and according to quick load a couple at 72k psi)
Heres the expander stems I use in a standard Lee powder through die to open up the cases and the roller tool. Any nick in the case neck will result in a split case. By going to 1.455" long and cutting them off at the shoulder you won't have to deal with all of that and still end up with a respectable round.

after looking over some load data for the 357 and the 7.62x25 I have found their is not that mutch diffrence in max load CUP pressure so blow back it will be. I would like to build one in 45acp but cost of a reamer and barrel is too mutch right now I have found a chamberd 357 barrel and mags that should work (or made to) are really cheep and 357 or reformd .223 brass to a rimless 357.
moleman you may have twisted my arm on a 357 max fal. muttman

The only real issue I've had so far is mags since I used an ar15. Most mags have a bullet feed guide which makes the front of the mag narrower than the back causing the rounds to single stack in the front and double stack in the back. Since the rounds are basically cylinders that causes problems after about 3 rounds. Pmags have a bullet feed guide that can be removed allowing a near full mag. I don't know how the fal or ak mags would work out as I sold those guns a few years back, but where there's a will there's a way. So far the 357AR is getting around 2396FPS with 158gr bullets (max load of W296) and 2268fps with 180gr bullets (again max loads of W296). 250gr bullets are around 1700fps. I haven't got to 200 gr bullets, but I suspect they should be in the mid 1900's to low 2000 fps. I realize you can load a 35rem hotter which pretty much blows the 357AR out of the water, but looking at a speer #11 book the 357AR loads are right on par with the 35rem which only operates around 35kPSI.

I realize you can load a 35rem hotter which pretty much blows the 357AR out of the water, but looking at a speer #11 book the 357AR loads are right on par with the 35rem which only operates around 35kPSI.

I have a 358 win reamer laying here that will beat both of them On a AK an I can use 308 brass necked up

I've been thinking of another 357 build that can perhaps top this one, but I won't be able to get to it until at least spring. An AK build though opens up the case head size and length quite a bit over the ar and a 358 win would be a winner IMHO.

Molman,
If I do a Fal in this cal I would be using .223 AK mags. I was thinking of an AK in .35rem but the case is too long for the mag. an adapter for AK mags is a lot easyer to do. Dang it Ill be sending you a pm here soon.
BG,
I still have not found if sombody has evin tryed this yet, I would bet it has. I just need some time to look.
I need some time to try and form a case, still working on my 5.45 reloading.
Muttman

Rimmed cases are a PITA to get firing. Still working on a mag for the .45-70 that doesn't require fabrication from the ground-up since PSL mags only hold a few rounds.

Look at any rimmed mag, .22 mags up to D.E. mags. The stacking is the trick. Stack the rounds in the wrong mag, and they might tip enough in the mag to allow the rims to ride over each other, making the top round an accidental bolt hold-open. Like what happens with a Mosin if you load it wrong. The mag has to have a shape that makes for consistent feeding. Perhaps look at a .30 carbine mag for a donor. For that matter you could possibly use a D.E. mag. (There is a DE in .357 right?)

So making the predictable stacking is the trick. Obviously a single-stack design would be easier. If that Galil mag works without letting the cases tip then you are all set. If you DO get it to work my dad will probably want me to build one for his .357/44 Bain & Davis wildcats! (a .347/44 B&D is a .44 mag case necked to .357).

that Galil mag will need a bunch of tweeks an will need to be shimed to fire single stack

a 35 remington or any oterh longer build is not that much harder. just opent he mag well up move the trigger guard back, deal with the cross meamber hitting an weld some taps off a ak mag onto what ever mag firts your rund the best. not any harder than getting a 357 mag not feed an load.

NOT PLUG AN PLAY BUY NOT THAT HARD. TAKE A GOOD LOOK AT A SAGIA RECIVER AN COPY IT. USE SAIGA 308 MAGS IF YOU NEED TO PRICY BUT NOT REDICULAS.. YOUR NOT GOING TO NEED A DOZEN MAGS FOR ANY OF THESE HIGHER POWER RIFLES FOR ANY REAL WORLD REASON. A FAL MAG IS A GOOD CANIDATE AS IS M14. I can mage a g3 fit with some work an thre dirt cheap.